re PR libstdc++/33815 (tr1::uniform_int isn't uniform)

2007-10-19  Paolo Carlini  <pcarlini@suse.de>

	PR libstdc++/33815
	* include/tr1_impl/random
	(uniform_int<>::_M_call(_UniformRandomNumberGenerator&, result_type,
	result_type, true_type)): Avoid the modulo (which uses the low-order
	bits).

From-SVN: r129493

libstdc++-v3/ChangeLog

 2007-10-19  Paolo Carlini  <pcarlini@suse.de>
 
+	PR libstdc++/33815
+	* include/tr1_impl/random
+	(uniform_int<>::_M_call(_UniformRandomNumberGenerator&, result_type,
+	result_type, true_type)): Avoid the modulo (which uses the low-order
+	bits).
+
+2007-10-19  Paolo Carlini  <pcarlini@suse.de>
+
 	* include/bits/stl_algobase.h (struct __cm_assign,
 	struct __copy_move, struct __copy_move_backward, move,
 	move_backward): Add.

libstdc++-v3/include/tr1_impl/random

@@ -1605,9 +1605,13 @@ _GLIBCXX_BEGIN_NAMESPACE_TR1
         _M_call(_UniformRandomNumberGenerator& __urng,
 		result_type __min, result_type __max, true_type)
         {
+	  // XXX Must be fixed to also work when __urng.max() - __urng.min()
+	  // is smaller than __max - __min.
 	  typedef typename __gnu_cxx::__add_unsigned<typename
 	    _UniformRandomNumberGenerator::result_type>::__type __utype;
-	  return result_type(__utype(__urng()) % (__max - __min + 1)) + __min; 
+	  return result_type((__max - __min + 1.0L) * __utype(__urng())
+			     / (__utype(__urng.max())
+				- __utype(__urng.min()) + 1.0L)) + __min;
 	}
 
       template<typename _UniformRandomNumberGenerator>